MEMBRANE COMPRISING SELF-ASSEMBLED BLOCK COPOLYMER AND PROCESS FOR PRODUCING THE SAME BY SPRAY COATING (IIc)

ABSTRACT

Disclosed are membranes formed from self-assembling block copolymers, for example, a diblock copolymer of the formula (I): 
     
       
         
         
             
             
         
       
     
     wherein R 1 —R 4 , n, and m are as described herein, which find use in preparing nanoporous membranes. Embodiments of the membranes contain the block copolymer that self-assembles into a cylindrical morphology. Also disclosed is a method of preparing such membrane which involves spray coating a polymer solution containing the diblock copolymer to obtain a thin film, followed by annealing the thin film in a solvent vapor and/or soaking in a solvent or mixture of solvents to form a nanoporous membrane.

CROSS-REFERENCE TO A RELATED APPLICATION

This patent application claims the benefit of U.S. ProvisionalApplication No. 62/005,753, filed May 30, 2014, which is incorporatedherein by reference in its entirety for all purposes.

BACKGROUND OF THE INVENTION

Membranes, particularly nanoporous membranes, are known to haveapplications in a number of areas including filtration of biologicalfluids, removal of micropollutants, water softening, wastewatertreatment, retention of dyes, preparation of ultrapure water in theelectronics industry, and concentration of food, juice, or milk. Methodsinvolving block copolymers, which self-assemble into nanostructures,have been proposed for preparing nanoporous membranes. Whileself-assembled structures are advantageous in that they producemembranes with uniform pore size and pore size distribution, challengesor difficulties remain with the proposed block copolymers and methods.For example, in some of these methods, a film is produced first from ablock copolymer, which is then followed by the removal of one of theblocks of the block copolymer by employing a harsh chemical such asstrong acid or strong base.

The foregoing indicates that there is an unmet need for membranes madefrom block copolymers that are capable of self-assembling intonanostructures and for a method for producing nanoporous membranes fromthese block copolymers, which does not require a removal of one of theblocks after a nanostructure is formed.

BRIEF SUMMARY OF THE INVENTION

The invention provides a porous membrane comprising a diblock copolymerof the formula (I):

wherein:

R¹ is a C₁-C₂₂ alkyl group optionally substituted with a substituentselected from halo, alkoxy, alkylcarbonyl, alkoxycarbonyl, amido, andnitro, or a C₃-C₁₁ cycloalkyl group, optionally substituted with asubstituent selected from alkyl, halo, alkoxy, alkylcarbonyl,alkoxycarbonyl, amido, and nitro;

R² is a C₆-C₂₀ aryl group or a heteroaryl group, optionally substitutedwith a substituent selected from hydroxy, amino, halo, alkoxy,alkylcarbonyl, alkoxycarbonyl, amido, and nitro;

one of R³ and R⁴ is a C₆-C₁₄ aryl group, optionally substituted with asubstituent selected from hydroxy, halo, amino, and nitro, and the otherof R³ and R⁴ is a C₁-C₂₂ alkoxy group, optionally substituted with asubstituent selected from carboxy, amino, mercapto, alkynyl, alkenyl,halo, azido, and heterocyclyl;

n and m are independently about 10 to about 2000.

The invention also provides a method for preparing the above membranecomprising:

(i) dissolving the diblock copolymer in a solvent system to obtain apolymer solution;

(ii) spray coating the polymer solution onto a substrate;

(iii) annealing the coating obtained in (ii) in a vapor comprising asolvent or a mixture of solvents to obtain a self-assembled structure;and optionally

(iv) annealing or soaking the self-assembled structure obtained in (iii)in a solvent or mixture of solvents to obtain a porous membrane.

The invention also provides composite membranes, for example, acomposite membrane comprising at least two layers, the first layer beingthe porous membrane as described above and the second layer being aporous support.

The present invention takes advantage of the ability of the blockcopolymers having thermodynamically incompatible blocks to undergo phaseseparation and self-assemble into nanostructures, thereby creatingnanoporous membranes having uniform porosity.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 depicts the overlaid traces of the Multi-angle Laser LightScattering (MALS) gel permeation chromatograms (GPC) of a homopolymer 1(a precursor to the diblock copolymer), a diblock copolymer precursor 2,and the diblock copolymer 3 in accordance with an embodiment of theinvention.

FIG. 2A depicts the AFM topographic image of the height of the surfaceof the thin film after spray coating but without annealing in accordancewith an embodiment of the invention and FIG. 2B depicts the AFMtopographic image of the phase of the surface of the thin film. FIG. 2Cdepicts the line profile extracted from FIG. 2B.

FIG. 3A depicts AFM topographic image of the height of the surface of aporous membrane prepared from the thin film depicted in FIG. 2A, afterannealing, and FIG. 3B depicts the AFM topographic image of the phase ofthe surface of the membrane.

FIG. 4A depicts the AFM image of the cross-section of a thin film spraycoated on a glass surface. FIG. 4B depicts a higher magnification AFMimage of the thin film depicted in FIG. 4A.

DETAILED DESCRIPTION OF THE INVENTION

In an embodiment, the invention provides a porous membrane comprising ablock copolymer of the formula (I) or (II):

wherein:

R¹ is a C₁-C₂₂ alkyl group optionally substituted with a substituentselected from halo, alkoxy, alkylcarbonyl, alkoxycarbonyl, amido, andnitro, or a C₃-C₁₁ cycloalkyl group, optionally substituted with asubstituent selected from alkyl, halo, alkoxy, alkylcarbonyl,alkoxycarbonyl, amido, and nitro;

R² is a C₆-C₂₀ aryl group or a heteroaryl group, optionally substitutedwith a substituent selected from hydroxy, amino, halo, alkoxy,alkylcarbonyl, alkoxycarbonyl, amido, and nitro;

one of R³ and R⁴ is a C₆-C₁₄ aryl group, optionally substituted with asubstituent selected from hydroxy, halo, amino, and nitro, and the otherof R³ and R⁴ is a C₁-C₂₂ alkoxy group, optionally substituted with asubstituent selected from carboxy, amino, mercapto, alkynyl, alkenyl,halo, azido, and heterocyclyl;

n and m are independently about 10 to about 2000.

In Formula (II), broken bonds indicate partial hydrogenation.Preferably, x is 0.1 to n and y is 0.1 to m. When x=n, the correspondingblock is fully hydrogenated. Similarly, when y=m, the correspondingblock is fully hydrogenated. In accordance with embodiments, x/n and y/mare independently 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

In an embodiment, the invention provides a method for preparing a porousmembrane comprising a block copolymer of the formula (I) or (II):

wherein:

R¹ is a C₁-C₂₂ alkyl group optionally substituted with a substituentselected from halo, alkoxy, alkylcarbonyl, alkoxycarbonyl, amido, andnitro, or a C₃-C₁₁ cycloalkyl group, optionally substituted with asubstituent selected from alkyl, halo, alkoxy, alkylcarbonyl,alkoxycarbonyl, amido, and nitro;

R² is a C₆-C₂₀ aryl group or a heteroaryl group, optionally substitutedwith a substituent selected from hydroxy, amino, halo, alkoxy,alkylcarbonyl, alkoxycarbonyl, amido, and nitro;

one of R³ and R⁴ is a C₆-C₁₄ aryl group, optionally substituted with asubstituent selected from hydroxy, halo, amino, and nitro, and the otherof R³ and R⁴ is a C₁-C₂₂ alkoxy group, optionally substituted with asubstituent selected from carboxy, amino, mercapto, alkynyl, alkenyl,halo, azido, and heterocyclyl;

n and m are independently about 10 to about 2000;

the method comprising:

(i) dissolving the diblock copolymer in a solvent system to obtain apolymer solution;

(ii) spray coating the polymer solution onto a substrate;

(iii) annealing the coating obtained in (ii) in a vapor comprising asolvent or a mixture of solvents to obtain a self-assembled structure;and optionally

(iv) annealing or soaking the self-assembled structure obtained in (iii)in a solvent or mixture of solvents to obtain a porous membrane.

In accordance with an embodiment, the above diblock copolymer is of theformula (Ia), wherein the monomers are exo isomers:

In any of the embodiments above, R¹ is a C₆-C₂₀ alkyl group optionallysubstituted with a substituent selected from halo, alkoxy,alkylcarbonyl, alkoxycarbonyl, amido, and nitro, or a C₃-C₁₁ cycloalkylgroup, optionally substituted with a substituent selected from alkyl,halo, alkoxy, alkylcarbonyl, alkoxycarbonyl, amido, and nitro.

In an embodiment, R¹ is a C₁₀-C₁₈ alkyl group, optionally substitutedwith a substituent selected from halo, alkoxy, alkylcarbonyl,alkoxycarbonyl, amido, and nitro.

In a particular embodiment, R¹ is a C₁₆ alkyl group.

In any of the embodiments above, R² is a C₆-C₁₀ aryl group, optionallysubstituted with a substituent selected from hydroxy, amino, halo,alkoxy, alkylcarbonyl, alkoxycarbonyl, amido, and nitro.

In an embodiment, R² is a phenyl group, optionally substituted with asubstituent selected from hydroxy, amino, halo, alkoxy, alkylcarbonyl,alkoxycarbonyl, amido, and nitro;

In any of the embodiments above, R³ is a C₆-C₁₄ aryl group, optionallysubstituted with a substituent selected from hydroxy, halo, amino, andnitro and R⁴ is a C₁-C₂₂ alkoxy group, optionally substituted with asubstituent selected from carboxy, amino, mercapto, alkynyl, alkenyl,halo, azido, and heterocyclyl.

In an embodiment, R³ is phenyl, optionally substituted with asubstituent selected from hydroxy, halo, amino, and nitro and R⁴ is aC₁-C₆ alkoxy group, optionally substituted with a substituent selectedfrom carboxy, amino, mercapto, alkynyl, alkenyl, halo, azido, andheterocyclyl.

In an embodiment, R³ is provided by the ROMP catalyst employed for thepolymerization of the monomers.

In an embodiment, R⁴ is a group provided by the vinyl ether compoundemployed for terminating the polymerization.

In accordance with the invention, the term “aryl” refers to a mono, bi,or tricyclic carbocyclic ring system having one, two, or three aromaticrings, for example, phenyl, naphthyl, anthracenyl, or biphenyl. The term“aryl” refers to an unsubstituted or substituted aromatic carbocyclicmoiety, as commonly understood in the art, and includes monocyclic andpolycyclic aromatics such as, for example, phenyl, biphenyl, naphthyl,anthracenyl, pyrenyl, and the like. An aryl moiety generally containsfrom, for example, 6 to 30 carbon atoms, preferably from 6 to 18 carbonatoms, more preferably from 6 to 14 carbon atoms and most preferablyfrom 6 to 10 carbon atoms. It is understood that the term aryl includescarbocyclic moieties that are planar and comprise 4n+2 π electrons,according to Hückel's Rule, wherein n=1, 2, or 3.

In accordance with the invention, the term “heteroaryl” refers to acyclic aromatic radical having from five to ten ring atoms of which atleast one atom is O, S, or N, and the remaining atoms are carbon.Examples of heteroaryl radicals include pyridyl, pyrazinyl, pyrimidinyl,pyrrolyl, pyrazolyl, imidazolyl, thiazolyl, oxazolyl, isooxazolyl,thiadiazolyl, oxadiazolyl, thiophenyl, furanyl, quinolinyl, andisoquinolinyl. The term “heteroaryl” as used herein, means a monocyclicheteroaryl or a bicyclic heteroaryl. The monocyclic heteroaryl is afive- or six-membered ring. The five-membered ring consists of twodouble bonds and one sulfur, nitrogen or oxygen atom. Alternatively, thefive-membered ring has two double bonds and one, two, three or fournitrogen atoms and optionally one additional heteroatom selected fromoxygen or sulfur, and the others carbon atoms. The six-membered ringconsists of three double bonds, one, two, three or four nitrogen atoms,and the others carbon atoms. The bicyclic heteroaryl consists of amonocyclic heteroaryl fused to a phenyl, or a monocyclic heteroarylfused to a monocyclic cycloalkyl, or a monocyclic heteroaryl fused to amonocyclic cycloalkenyl, or a monocyclic heteroaryl fused to amonocyclic heteroaryl. The monocyclic and the bicyclic heteroaryl areconnected to the parent molecular moiety through any substitutable atomcontained within the monocyclic or the bicyclic heteroaryl. Themonocyclic and bicyclic heteroaryl groups of the present invention canbe substituted or unsubstituted. In addition, the nitrogen heteroatommay or may not be quaternized, and may or may not be oxidized to theN-oxide. Also, the nitrogen containing rings may or may not beN-protected. Representative examples of monocyclic heteroaryl include,but are not limited to, furanyl, imidazolyl, isoxazolyl, isothiazolyl,oxadiazolyl, oxazolyl, pyridinyl, pyridine-N-oxide, pyridazinyl,pyrimnidinyl, pyrazinyl, pyrazolyl, pyrrolyl, tetrazolyl, thiadiazolyl,thiazolyl, thienyl, triazolyl, and triazinyl. Representative examples ofbicyclic heteroaryl groups include, but not limited to, benzothienyl,benzoxazolyl, benzimidazolyl, benzoxadiazolyl,6,7-dihydro-1,3-benzothiazolyl, imidazo[1,2-a]pyridinyl, indazolyl,1H-indazol-3-yl, indolyl, isoindolyl, isoquinolinyl, naphthyridinyl,pyridoimidazolyl, quinolinyl, quinolin-8-yl, and5,6,7,8-tetrahydroquinolin-5-yl.

The “alkyl” group could be linear or branched. In accordance with anembodiment, the alkyl group is preferably a C₁-C₂₂ alkyl. Examples ofalkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl,sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl,hexadecyl, and the like. This definition also applies wherever “alkyl”occurs such as in hydroxyalkyl, monohalo alkyl, dihalo alkyl, andtrihalo alkyl. The C₁-C₂₂ alkyl group can also be further substitutedwith a cycloalkyl group, e.g., a C₃-C₁₁ cycloalkyl group.

The “cycloalkyl” group can be monocyclic or bicyclic. Examples ofmonocyclic cycloalkyl groups include cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl. Examples ofbicyclic cycloalkyl groups include those with one common ring carbonatom such as spirooctane, spirononane, spirodecane, and spiroundecane,and those with two common ring carbon atoms such as bicyclooctane,bicyclononane, bicyclodecane, and bicycloundecane. Any of the cycloalkylgroups could be optionally substituted with one or more alkyl groups,e.g., C₁-C₆ alkyl groups.

In accordance with an embodiment, the “alkoxy” group is preferably aC₁-C₂₂ alkoxy. Examples of alkoxy group include methoxy, ethoxy,n-propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy,n-pentoxy, isopentoxy, n-hexoxy, hexadecyloxy, and the like.

The term “halo” refers to a halogen selected from the group consistingof fluorine, chlorine, bromine, and iodine, preferably chlorine orbromine.

The term “heterocycle” or “heterocyclic” as used herein, means amonocyclic heterocycle or a bicyclic heterocycle. The monocyclicheterocycle is a three-, four-, five-, six- or seven-membered ringcontaining at least one heteroatom independently selected from the groupconsisting of O, N, N(H) and S. The three- or four-membered ringcontains zero or one double bond and a heteroatom selected from thegroup consisting of O, N, N(H) and S. The five-membered ring containszero or one double bond, and one, two or three heteroatoms selected fromthe group consisting of O, N, N(H) and S. The six-membered ring containszero, one or two double bonds and one, two or three heteroatoms selectedfrom the group consisting of O, N, N(H) and S. The seven-membered ringcontains zero, one, two, or three double bonds and one, two or threeheteroatoms selected from the group consisting of O, N, N(H) and S. Themonocyclic heterocycle can be unsubstituted or substituted and isconnected to the parent molecular moiety through any substitutablecarbon atom or any substitutable nitrogen atom contained within themonocyclic heterocycle. Representative examples of monocyclicheterocycle include, but are not limited to, azetidinyl, azepanyl,aziridinyl, diazepanyl, [1,4]diazepan-1-yl, 1,3-dioxanyl,1,3-dioxolanyl, 1,3-dithiolanyl, 1,3-dithianyl, homomorpholinyl,homopiperazinyl, imidazolinyl, imidazolidinyl, isothiazolinyl,isothiazolidinyl, isoxazolinyl, isoxazolidinyl, morpholinyl,oxadiazolinyl, oxadiazolidinyl, oxazohnyl, oxazolidinyl, piperazinyl,piperidinyl, pyranyl, pyrazolinyl, pyrazolidinyl, pyrrolinyl,pyrrolidinyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydrothienyl,thiadiazolinyl, thiadiazolidinyl, thiazolinyl, thiazolidinyl,thiomorpholinyl, 1,1-dioxidothiomorpholinyl(thiomorpholine sulfone),thiopyranyl, and trithianyl. The bicyclic heterocycle is a monocyclicheterocycle fused to a phenyl group, or a monocyclic heterocycle fusedto a monocyclic cycloalkyl, or a monocyclic heterocycle fused to amonocyclic cycloalkenyl, a monocyclic heterocycle fused to a monocyclicheterocycle, or a monocyclic heterocycle fused to a monocyclicheteroaryl. The bicyclic heterocycle is connected to the parentmolecular moiety through any substitutable carbon atom or anysubstitutable nitrogen atom contained within the bicyclic heterocycleand can be unsubstituted or substituted. Representative examples ofbicyclic heterocycle include, but are not limited to, benzodioxinyl,benzopyranyl, thiochromanyl, 2,3-dihydroindolyl, indolizinyl,pyranopyridinyl, 1,2,3,4-tetrahydroisoquinolinyl,1,2,3,4-tetrahydroquinolinyl, thiopyranopyridinyl,2-oxo-1,3-benzoxazolyl, 3-oxo-benzoxazinyl, 3-azabicyclo[3.2.0]heptyl,3,6-diazabicyclo[3.2.0]heptyl, octahydrocyclopenta[c]pyrrolyl,hexahydro-1H-furo[3,4-c]pyrrolyl, octahydropyrrolo[3,4-c]pyrrolyl,2,3-dihydrobenzofuran-7-yl, 2,3-dihydrobenzofuran-3-yl, and3,4-dihydro-2H-chromen-4-yl. The monocyclic or bicyclic heterocycles asdefined herein may have two of the non-adjacent carbon atoms connectedby a heteroatom selected from N, N(H), O or S, or an alkylene bridge ofbetween one and three additional carbon atoms. Representative examplesof monocyclic or bicyclic heterocycles that contain such connectionbetween two non-adjacent carbon atoms include, but not limited to,2-azabicyclo[2.2.2]octyl, 2-oxa-5-azabicyclo[2.2.2]octyl,2,5-diazabicyclo[2.2.2]octyl, 2-azabicyclo[2.2.1]heptyl,2-oxa-5-azabicyclo[2.2.1]heptyl, 2,5-diazabicyclo[2.2.1]heptyl,2-azabicyclo[2.1.1]hexyl, 5-azabicyclo[2.1.1]hexyl,3-azabicyclo[3.1.1]heptyl, 6-oxa-3-azabicyclo[3.1.1]heptyl,8-azabicyclo[3.2.1]octyl, 3-oxa-8-azabicyclo[3.2.1]octyl,1,4-diazabicyclo[3.2.2]nonyl, 1,4-diazatricyclo[4.3.1.1 3,8]undecyl,3,10-diazabicyclo[4.3.1]decyl, or 8-oxa-3-azabicyclo[3.2.1]octyl,octahydro-1H-4,7-methanoisoindolyl, andoctahydro-1H-4,7-epoxyisoindolyl. The nitrogen heteroatom may or may notbe quaternized, and may or may not be oxidized to the N-oxide. Inaddition, the nitrogen containing heterocyclic rings may or may not beN-protected.

Examples of heterocyclyl groups include pyridyl, piperidinyl,piperazinyl, pyrazinyl, pyrolyl, pyranyl, tetrahydropyranyl,tetrahydrothiopyranyl, pyrrolidinyl, furanyl, tetrahydrofuranyl,thiophenyl, tetrahydrothiophenyl, purinyl, pyrimidinyl, thiazolyl,thiazolidinyl, thiazolinyl, oxazolyl, triazolyl, tetrazolyl, tetrazinyl,benzoxazolyl, morpholinyl, thiophorpholinyl, quinolinyl, andisoquinolinyl.

Five-membered unsaturated heterocyclics with and without benzo: furanyl,thiopheneyl, pyrrolyl, pyrazolyl, pyrazolinyl, imidazolyl, imidazolinyl,dithiazolyl, furazanyl, 1,2,3-triazolyl, tetrazolyl, 1,2,4-triazolyl,oxadiazolyl, thiadiazolyl, isoxazolyl, isoxazolinyl, oxazolyl,oxazolinyl, phospholyl, isothiazolyl, thiazolyl, thiazolinyl,isothiazolyl, isothiazolidinyl, benzofuranyl, benzothiopheneyl, indolyl,benzimidazolyl, benzoxazolinyl, and benzothiazolinyl.

Whenever a range of the number of atoms in a structure is indicated(e.g., a C₁₋₂₂, a C₁₋₁₂, C₁₋₈, C₁₋₆, or C₁₋₄ alkyl, alkoxy, etc.), it isspecifically contemplated that any sub-range or individual number ofcarbon atoms falling within the indicated range also can be used. Thus,for instance, the recitation of a range of 1-22 carbon atoms (e.g.,C₁-C₂₂), 1-20 carbon atoms (e.g., C₁-C₂₀), 1-18 carbon atoms (e.g.,C₁-C₂₀), 1-16 carbon atoms (e.g., C₁-C₁₆), 1-14 carbon atoms (e.g.,C₁-C₁₄), 1-12 carbon atoms (e.g., C₁-C₁₂), 1-10 carbon atoms (e.g.,C₁-C₁₀), 1-8 carbon atoms (e.g., C₁-C₈), 1-6 carbon atoms (e.g., C₁-C₆),1-4 carbon atoms (e.g., C₁-C₄), 1-3 carbon atoms (e.g., C₁-C₃), or 2-8carbon atoms (e.g., C₂-C₈) as used with respect to any chemical group(e.g., alkyl, alkoxy, alkylamino, etc.) referenced herein encompassesand specifically describes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 17, 18, 19, 20, 21, or 22 carbon atoms, as appropriate, aswell as any sub-range thereof, e.g., 1-2 carbon atoms, 1-3 carbon atoms,1-4 carbon atoms, 1-5 carbon atoms, 1-6 carbon atoms, 1-7 carbon atoms,1-8 carbon atoms, 1-9 carbon atoms, 1-10 carbon atoms, 1-11 carbonatoms, 1-12 carbon atoms, 1-13 carbon atoms, 1-14 carbon atoms, 1-15carbon atoms, 1-16 carbon atoms, 1-17 carbon atoms, 1-18 carbon atoms,1-19 carbon atoms, 1-20 carbon atoms, 1-21 carbon atoms, and 1-22 carbonatoms, and anything in between such as 2-3 carbon atoms, 2-4 carbonatoms, 2-5 carbon atoms, 2-6 carbon atoms, 2-7 carbon atoms, 2-8 carbonatoms, 2-9 carbon atoms, 2-10 carbon atoms, 2-11 carbon atoms, 2-12carbon atoms, 2-12 carbon atoms, 2-13 carbon atoms, 2-14 carbon atoms,2-15 carbon atoms, 2-16 carbon atoms, 2-17 carbon atoms, 2-18 carbonatoms, 2-19 carbon atoms, 2-20 carbon atoms, 2-21 carbon atoms, and 2-22carbon atoms, 3-4 carbon atoms, 3-5 carbon atoms, 3-6 carbon atoms, 3-7carbon atoms, 3-8 carbon atoms, 3-9 carbon atoms, 3-10 carbon atoms,3-11 carbon atoms, 3-12 carbon atoms, 3-13 carbon atoms, 3-14 carbonatoms, 3-15 carbon atoms, 3-16 carbon atoms, 3-17 carbon atoms, 3-18carbon atoms, 3-19 carbon atoms, 3-20 carbon atoms, 3-21 carbon atoms,and 3-22 carbon atoms, and 4-5 carbon atoms, 4-6 carbon atoms, 4-7carbon atoms, 4-8 carbon atoms, 4-9 carbon atoms, 4-10 carbon atoms,4-11 carbon atoms, 4-12 carbon atoms, 4-13 carbon atoms, 4-14 carbonatoms, 4-15 carbon atoms, 4-16 carbon atoms, 4-17 carbon atoms, 4-18carbon atoms, 4-19 carbon atoms, 4-20 carbon atoms, 4-21 carbon atoms,4-22 carbon atoms, etc., as appropriate.

In the above embodiments, “n” and “m” represent the average degree ofpolymerization of the respective monomers.

In accordance with embodiments of the invention, n is about 10 to about1000, about 10 to about 500, about 10 to about 250, about 20 to about1000, about 20 to about 500, about 20 to about 250, about 30 to about1000, about 30 to about 500, about 30 to about 250, about 40 to about1000, about 40 to about 500, about 40 to about 250, about 50 to about1000, about 50 to about 500, about 50 to about 250, about 60 to about1000, about 60 to about 500, or about 60 to about 250.

In any of the above embodiments, m is about 50 to about 2000, about 50to about 1500, about 50 to about 1000, about 100 to about 2000, about100 to about 1500, about 100 to about 1000, about 150 to about 2000,about 150 to about 1500, about 150 to about 1000, about 200 to about2000, about 200 to about 1500, or about 200 to about 1000.

In any of the above embodiments, n is typically about 10 to about 200,preferably about 20 to about 190, more preferably about 30 to about 140,and even more preferably 105.

In any of the above embodiments of the block copolymer, m is typicallyabout 50 to about 2000, preferably about 675 to about 1525, morepreferably about 675 to about 1120, and even more preferably 870.

In an embodiment, n is about 10 to about 200 and m is about 80 to about160.

The block copolymer, for example, diblock copolymer, can have anysuitable total molecular weight, for example, a number average molecularweight (M_(n)) of from about 50 kDa to about 1000 kDa; in certainembodiments, the block copolymer has an M_(n) of from about 100 kDa toabout 600 kDa; in certain other embodiments, the block copolymer has anM_(n) of from about 180 kDa to about 500 kDa; and in furtherembodiments, the block copolymer has an M_(n) of from about 195 kDa toabout 441 kDa. In certain embodiments, the block copolymer has an M_(n)of from about 250 kDa to 500 kDa.

In accordance with embodiment, if double bonds are present in the blockcopolymer, the double bonds can have any suitable orientation, cis,trans, and the cis and the trans forms can be distributed in a randommanner.

The block copolymer, particularly the diblock copolymer, mayself-assemble into any suitable morphology, for example, but not limitedto, cylindrical morphology, lamellar morphology, or double gyroidmorphology. The type of nanostructure into which the copolymersself-assemble would depend, among others, on the volume fraction of thetwo blocks in the block copolymer as well as the nature of the solventsystem.

For example, in a diblock copolymer, at a polymer volume fraction ratiorange (f_(A):f_(B)) of the two monomers of 37-50:63-50, formation of alamellar morphology involving a stack of layers of equivalent domainsize is favored, at a volume fraction ratio range of 15-70:85-30,formation of a cylindrical morphology where the minor polymer componentforms cylinders in a matrix of major polymer block component is favored,and at a volume fraction ratio range of 7-15:83-85, formation of bodycentered cubic phase where the minor polymer component forms spheres ina matrix of the major polymer block component is favored. At a volumefraction ratio range of 33-37:67-33, formation of a double gyroidmorphology is favored.

Cylindrical morphology includes a phase domain morphology havingdiscrete tubular or cylindrical shapes. The tubular or cylindricalshapes may be hexagonally packed on a hexagonal lattice. In embodiments,the cylindrical domain size is from about 5 nm to about 100 nm.

Lamellar morphology includes a phase domain morphology having layers ofalternating compositions that are generally oriented parallel withrespect to one another. In embodiments, the lamellar domain size is fromabout 5 nm to about 100 nm.

The double gyroid morphology comprises two interpenetrating continuousnetwork. In embodiments, the double gyroid domain size is from about 5nm to about 100 nm.

In an embodiment, the polymerized second monomer (bearing R²) and thepolymerized first monomer (bearing R¹) are present in the diblockcopolymer in any suitable volume fraction. For example, the % volumefraction of the first monomer to that of the second monomer can be inthe range of about 15:about 85 to about 30:about 70, preferably in therange of about 19:about 81 to about 25:about 75, and more preferablyabout 20:about 80. In an embodiment, the volume fraction of the secondmonomer is about 80%, and the mass fraction is about 83%, of the totalpolymer.

In an embodiment, the polymer volume fraction of the second monomer tothat of the first monomer is about 2.3 to about 5.6:1, which favors theformation of a cylindrical morphology. In a preferred embodiment, thepolymer volume fraction of the second monomer to that of the firstmonomer is about 4:1.

In a specific embodiment, the membrane comprises a diblock copolymer offormula (I) has the following structure, in particular, wherein n is 105and m is 870:

In an embodiment, the membrane comprises the diblock copolymer offormula (I) has the following structure where the monomers were in theexo configuration, in particular, wherein n is 105 and m is 870:

The diblock copolymers described above can be prepared by a methodcomprising:

(i) polymerizing one of the two monomers of the formulas:

with a ring opening metathesis polymerization (ROMP) catalyst to obtaina ring-opened polymer having a living chain end;

(ii) polymerizing the other of the two monomers on the living end of thering-opened polymer obtained in (i) to obtain a diblock copolymer havinga living end; and

(iii) terminating the living end of the diblock copolymer obtained in(ii) with an optionally substituted alkyl vinyl ether; and

(iv) hydrogenating the diblock copolymer obtained in (iii) to obtain ablock copolymer of formula (I) or (II).

In the above method, the monomer that is first polymerized is of theformula:

After the polymerization of the above monomer, the second monomer thatis polymerized thereon is a monomer of the formula:

The first monomer and the second monomer can be in an exo or endosteroechemical configuration. In an embodiment, the first and secondmonomers are of the exo configuration, e.g., a monomer having the exoisomer at 98% or higher.

In the first and second monomers, R¹ and R² are the same as describedabove for the diblock copolymer of formula (I). The first and secondmonomers are (oxa)norbornene (di)carboxylic imide derived monomers. Themonomers can be prepared by any suitable method, for example, startingfrom maleimide and furan via a Diels-Alder reaction, illustrated below:

The first monomer can be synthesized via Mitsunobu Coupling reaction, asillustrated below:

Alternatively, the first monomer can be synthesized by the reaction ofexo-7-oxanorbornene-5,6-dicarboxyanhydride with hexadecylamine orN-hexadecyl-maleimide reaction with furan via a Diels-Alder reaction.

The second monomer can be synthesized via a Diels-Alder reaction betweenN-phenyl maleimide and furan in acetonitrile, as illustrated below.

The polymerization of the monomers is carried out by ring-opening olefinmetathesis polymerization (ROMP), in which a cyclic olefin monomer ispolymerized or copolymerized by ring-opening of the cyclic olefinmonomer. Typically a transition metal catalyst containing a carbeneligand mediates the metathesis reaction.

Any suitable ROMP catalyst can be used, for example, Grubbs' first,second, and third generation catalysts, Umicore, Hoveyda-Grubbs,Schrock, and Schrock-Hoveyda catalysts can be employed. Examples of suchcatalysts include the following:

In an embodiment, Grubbs' third generation catalysts are particularlysuitable due to their advantages such as stability in air, tolerance tomultiple functional groups, and/or fast polymerization initiation andpropagation rates. In addition, with the Grubbs' third generationcatalysts, the end groups can be engineered to accommodate anycompatible groups, and the catalyst can be recycled readily. A preferredexample of such a catalyst is:

The above third generation Grubbs catalyst (G3) may be obtainedcommercially or prepared from a Grubbs second generation catalyst (G2)as follows:

The first monomer and the second monomer are polymerized sequentially toobtain the diblock copolymer. Any of the two monomers can be polymerizedfirst. For example, the first monomer can be polymerized first, followedby the second monomer. Alternatively, the second monomer can bepolymerized first, followed by the first monomer.

Typically, the monomers have a chemical purity of at least 95%,preferably 99% or greater, and more preferably 99.9% or greater. It ispreferred that the monomers are free of impurities that will interferewith the polymerization, e.g., impurities that will affect the ROMPcatalyst. Examples of such impurities include amines, thiols(mercaptans), acids, phosphines, and N-substituted maleimides.

The polymerization of the monomers is conducted in a suitable solvent,for example, solvents generally used for conducting ROMPpolymerizations. Examples of suitable solvents include aromatichydrocarbons such as benzene, toluene, and xylene, aliphatichydrocarbons such as n-pentane, hexane, and heptane, alicylichydrocarbons such as cyclohexane, and halogenated hydrocarbons such asdichloromethane, dichloroethane, dichloroethylene, tetrachloroethane,chlorobenzene, dichlorobenzene, and trichlorobenzene, as well asmixtures thereof.

When polymerization is carried out in the organic solvent, the monomerconcentration can be in the range of 1 to 50 wt %, preferably 2 to 45 wt%, and more preferably 3 to 40 wt %.

The polymerization can be carried out at any suitable temperature, forexample, from −20 to +100° C., preferably 10 to 80° C.

The polymerization can be carried out for any period of time suitable toobtain the appropriate chain length of each of the blocks, which can befrom about 1 minute to 100 hours.

The amount of catalyst can be chosen in any suitable amount. Forexample, the molar ratio of the catalyst to the monomer can be about1:10 to about 1:1000, preferably about 1:50 to 1:500, and morepreferably about 1:100 to about 1:200. For example, the molar ratio ofthe catalyst to the monomer could be 1:n and 1:m, where n and m are theaverage degrees of polymerization.

After the polymerization of the two monomers, the chain end of thediblock copolymer is terminated by adding an optionally substitutedalkyl vinyl ether to the polymerization mixture.

The diblock copolymer can be isolated by suitable techniques such asprecipitation with a nonsolvent.

The resulting diblock copolymer precursor can be hydrogenated to obtaina block copolymer of formula (I) or (II). Hydrogenation can be carriedout by any suitable technique, for example, by the use of hydrogen gasand a catalyst. Any suitable catalyst, heterogeneous or homogeneous, canbe used. Examples of heterogeneous catalysts include Raney nickel,palladium-on-charcoal, NaBH₄-reduced nickel, platinum metal or itsoxide, rhodium, ruthenium, NaH—RONa—Ni(OAc)₂, and zinc oxide. Examplesof homogeneous catalysts include chlorotris(triphenylphosphine)rhodiumor Wilkinson's catalyst, andchlorotris(triphenylphosphine)hydridoruthenium (II).

Preferably, the diblock copolymer is hydrogenated by the use of hydrogengas and a second generation Grubbs catalyst. By varying the molar ratiobetween the polymer and the catalyst, varying degrees of hydrogenationcan be obtained. In an embodiment, a catalyst loading of about 1:100molar equivalent to the double bond ([G2]_(molar):[doublebond]_(molar)=about 1:100) to fully hydrogenate the precursor copolymer.The ratio can be varied from about 1:100 to about 1:500 or about 1:600,partially hydrogenated block copolymers can be obtained. The resultingcopolymers can be triblock, tetrablock or higher multiblock copolymers.

The starting homopolymer formed during the preparation of the diblockcopolymer precursor, and the diblock or multiblock copolymer of theinvention can be characterized for their molecular weights and molecularweight distributions by any known techniques. For example, a MALS-GPCtechnique can be employed. The technique uses a mobile phase to elute,via a high pressure pump, a polymer solution through a bank of columnspacked with a stationary phase. The stationary phase separates thepolymer sample according to the chain size followed by detecting thepolymer by three different detectors. A series of detectors can beemployed, e.g., an Ultraviolet detector (UV-detector), followed by amulti-angle laser light scattering detector (MALS-detector), which inturn, is followed by a refractive index detector (RI-detector) in a row.The UV-detector measures the polymer light absorption at 254 nmwavelength; the MALS-detector measures the scattered light from polymerchains relative to mobile phase.

The block copolymers of the invention are preferably highlymonodisperse. For example, the copolymers have an Mw/Mn of 1.01 to 1.2,preferably 1.05 to 1.10.

The present invention provides a porous membrane comprising a blockcopolymer described above.

In an embodiment, the porous membrane is prepared by a spray coatingprocess.

To prepare the membrane, the block copolymer is first dissolved in asuitable solvent or solvent system to obtain a polymer solution. Thepolymer solution can be prepared by any suitable method known to thoseskilled in the art. The block copolymer is added to the solvent systemand stirred until a homogeneous solution is obtained. If desired, thesolution can be stirred for an extended time to allow the blockcopolymer to assume its thermodynamically favorable structure in thesolution. The block copolymer is dissolved in a good solvent or amixture containing good solvents.

Embodiments of a suitable solvent system include a solvent or a mixtureof solvents selected from halogenated hydrocarbons, ethers, amides, andsulfoxides. In an embodiment, the solvent system includes a volatilesolvent, for example, a solvent having a boiling point less than 100° C.

For example, the solvent system includes a solvent or a mixture ofsolvents selected from dichloromethane, 1-chloropentane, chloroform,1,1-dichloroethane, N,N-dimethylformamide (DMF), N,N-dimethylacetamide(DMA), N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO),tetrahydrofuran (THF), 1,3-dioxane, and 1,4-dioxane.

Thus, for example, a mixture of DMF and THF, a mixture of NMP and THF,DMA and 1-chloropentane, a mixture of DMA and THF, a mixture of DMSO andTHF, a mixture of DMSO and 1-chloropentane, a mixture of NMP and1-chloropentane, a mixture of DMF and 1-chloropentane, a mixture of1,3-dioxane and THF, a mixture of 1,4-dioxane and THF, or a mixture of1,3- or 1,4 dioxane, DMF, and THF can be employed as the solvent system.

In a preferred embodiment, a mixture of DMF and THF, a mixture of DMAand THF, a mixture of DMA and 1-chloropentane, a mixture of DMSO andTHF, a mixture of 1,3-dioxane and THF, a mixture of 1,4-dioxane and THF,can be employed as the solvent system.

In a more preferred embodiment, a mixture of DMF and THF, a mixture ofDMA and 1-chloropentane, or a mixture of NMP and THF can be used as thesolvent system.

In the above embodiments, where a mixture of solvents is used as thesolvent system, the mixture can include any suitable ratio of thesolvents, for example, in a binary solvent mixture, either of thesolvents can be present in a volume or mass ratio of 80/20, 75/25,70/30, 65/35, 60/40, 55/45, or 50/50, or any ratio therebetween. In aternary solvent system, any of the three solvents can be present in anysuitable ratio, for example, a volume or mass ratio of 80/10/10,75/15/10, 70/20/10, 65/25/10, 60/30/10, 55/25/30, 40/40/20, or 30/30/40or any ratio therebetween.

The polymer solution can contain any suitable amount of the blockcopolymer. In accordance with an embodiment, the polymer solutioncontains about 2 to about 10% or more, preferably about 3 to about 8%,and more preferably about 4 to about 6% by weight of the blockcopolymer. In an example, the polymer solution contains about 5% byweight of the block copolymer. The polymer concentration can control thethickness of the film, and hence the thickness of the membrane obtained.The polymer concentration can also control the porosity of the membrane,with high concentrations producing less porous membrane.

In accordance with embodiments, the polymer solution contains DMF andTHF at a mass ratio of about 60:40.

The polymer solution is sprayed on a substrate such as glass plates,plastic films, woven or nonwoven fabrics, silicon wafer, or metalplates. Examples of fabrics include polyethylene, polypropylene,polyester, and nylon fabrics. The substrates can be porous or nonporous.A porous substrate can be soaked in a nonsolvent or imbibed with a watersoluble polymer such as polyvinyl alcohol or polyethylene glycol. Thesolution containing the block copolymer can be sprayed on to the thusprepared porous substrate.

The substrate surface has an influence on the resulting morphologyorientation, and the orientation or morphology outcome is determinedbased on the thermodynamic interaction between the substrate and eachblock within the diblock. If the substrate surface has favorableinteraction with one of the two blocks, the diblock copolymer willself-assemble in such a way that it maximizes the interaction byspreading and exposing the block that it has favorable interaction with.For example, in the case of cylinder morphology, the cylinder willinterface with the substrate surface in which the cylinder will beparallel to the surface if the substrate has higher affinity to oneblock than the other. If the substrate surface has neutral or littleaffinity toward either block, the cylinders will be aligned normal tothe substrate.

In accordance with an embodiment of the invention, the polymer solutionis atomized during the spraying process. Any suitable spraying processcan be used. The atomization can be airless or pressure activated, whichinvolves forcing the coating liquid through a small diameter nozzleunder high pressure. The fluid pressure can be between about 5 and about35 MPa (about 700 to about 5000 psi), and fluid flow rates can bebetween about 150 to about 1500 cm³/min. A suitable pump is designed todevelop such pressures, which can be driven mechanically, electrically,pneumatically, or hydraulically. The nozzle apertures can have diametersin the range of about 0.2 to about 2.0 mm. As the fluid is forcedthrough the nozzle, it accelerates to a high velocity and leaves thenozzle in a thin sheet or jet of liquid in the relatively motionlessambient air, producing a shear force between the fluid and the air. Thefluid is atomized by turbulent or aerodynamic disintegration. The mostcommon nozzles produce a long, narrow fan-shaped pattern of varioussizes; some produce a solid hollow cone. The airless atomization can beassisted with a small amount of compressed air at about 35 to about 170kPa (about 5 to about 25 psi). The air assists in obtaining improvedatomization at lower fluid pressures. In an embodiment, the coatingsolution can be mixed with a supercritical fluid, which tends to reducethe volatile organic compound emission.

Alternatively, the polymer solution can be electrostatically atomized oratomized in a bell (cup) or disk that rotates at a speed of about 10,000to about 40,000 rpm.

The film can be of any suitable thickness, for example, a thickness ofabout 10 to about 1000 nm, typically about 100 to about 500 nm.

The polymer solution is spray coated at any suitable temperature, forexample, at about 10° C. to about 40° C., preferably about 15° C. toabout 30° C., and more preferably about 20° C. to about 25° C.

The substrate can be stationary or moving. In an embodiment, thesubstrate is a moving belt, plastic film, or fabric.

The thin film of the polymer solution obtained by spray coating is thenannealed in two steps, wherein the first annealing urges the blockcopolymer into forming a self-assembled structure, for example, into astructure having minor and major domains. In an embodiment, the minordomains are cylindrical domains. The second annealing urges theformation of a porous membrane, for example, by the confined swelling ofthe minor domains. Any of the solvents identified above for the solventsystem can be employed as a solvent vapor to carry out the annealingsteps. For example, dichloromethane can be employed as a vapor.

Alternatively, instead of carrying out a second annealing, theself-assembled structure can be soaked in a solvent or mixture ofsolvents to obtain a porous membrane. The solvent or mixture of solventscan be at any suitable temperature, for example, from ambienttemperature, for example, 20° C. to 25° C., to elevated temperatures,such as up to 40° C., 50° C., 60° C., 70° C., 80° C., or 90° C. Any ofthe solvents used for annealing can be used for the soaking step.

Each of the annealing or the soaking step can be carried out for anysuitable length of time, for example, 0.1 hour to 1 month or more, 5hours to 15 days or more, or 10 hours to 10 days or more.

Without wishing to be bound by any theory or mechanism, the formation ofa nanostructure is believed to take place as follows. The blockcopolymer in solution experiences certain thermodynamic forces. Forexample, since the diblock copolymer comprises two chemically differentblocks of polymer chains connected by a covalent bond, there exists anincompatibility between the two blocks. In addition, there exists aconnectivity constraint imparted by the connecting covalent bond. As aresult of these thermodynamic forces, the diblock copolymer whendissolved in an appropriate solvent system self-assembles intomicro-phase separated domains that exhibit ordered morphologies atequilibrium. When a film is cast from a dilute solution, the diblockcopolymer forms micelles composed of a core and a corona, each made of adifferent block. In dilute solution, the micelles tend to be isolatedfrom each other. However, in concentrated solution, as for example, whenthe solvent is removed from a thin film of the solution by evaporation,the micelles tend to aggregate with the result that the coronas merge toform a continuous matrix and the cores merge to form porous channels.

The block copolymer's ability to form ordered structures depends on anumber of factors, including the polymer's relaxation rate, itsviscosity, its concentration, and the nature of the solvent, inparticular its chi parameter or the Hansen solubility parameter. Aneutral solvent to both the blocks tends to orient the cylindrical poresnormal to the membrane surface. The solvent system mediates theinteraction between the two blocks. As the system is annealed in thesolvent vapor, the polymer chain mobility increases leading to polymerrelaxation and formation of self-assembled ordered structures motivatedby chain incompatibility and as a result of free energy minimizationbetween the two blocks. Two competing thermodynamically deriving forcesgovern the process; the first is that the chains are chemicallyincompatible and have a tendency to segregate from each other, whichincreases system entropy, and the second is the restorative forceleading to a loss of entropy as the system retracts due to the chemicalbonds between monomer units and the diblock chains. The energyminimization occurs between these two competing factors. Accordingly,the choice of the solvent or solvent system is an important factor inobtaining ordered nanostructures.

The film is then washed in a water bath for a suitable length of time,e.g., from about 1 min to about 2 hr, to remove any residual solvents,and optionally dried, to obtain a nanoporous membrane in accordance withan embodiment of the invention.

In accordance with an embodiment, the porous membrane is a symmetricmembrane wherein the diblock copolymer is self-assembled into an orderedstructure and the pores extend through the thickness of the membrane. Inthe self-assembled structure, the diblock copolymer and the pores areordered in a cylindrical morphology and perpendicular to the plane ofthe membrane and the cylindrical pores whose diameters are in the rangeof about 40 to about 60 nm and the pores extend all the way down to thefilm thickness and at a depth of about 50 nm.

In accordance with another embodiment, the porous membrane is anasymmetric membrane comprising a first layer and a second layer, thefirst layer comprising the diblock copolymer having ordered pores, forexample, in a cylindrical morphology, and the second layer comprising apolymeric support having larger pores, for example, pores of diameter0.5 μm or more, e.g., 1 to 10 μm.

The polymeric support which serves as the second layer of the compositemembrane can be made of any suitable polymer, for example,polyaromatics; sulfones (e.g., polysulfones, including aromaticpolysulfones such as, for example, polyethersulfone (PES), polyetherether sulfone, bisphenol A polysulfone, polyarylsulfone, andpolyphenylsulfone), polyamides, polyimides, polyvinylidene halides(including polyvinylidene fluoride (PVDF)), polyolefins, such aspolypropylene and polymethylpentene, polyesters, polystyrenes,polycarbonates, polyacrylonitriles ((PANs) includingpolyalkylacrylonitriles), cellulosic polymers (such as celluloseacetates and cellulose nitrates), fluoropolymers, and polyetheretherketone (PEEK).

In accordance with an embodiment of the invention, the porous membraneis a nanoporous membrane, for example, a membrane having pores ofdiameter between 1 nm and 100 nm.

Membranes according to embodiments of the invention can be used in avariety of applications, including, for example, diagnostic applications(including, for example, sample preparation and/or diagnostic lateralflow devices), ink jet applications, filtering fluids for thepharmaceutical industry, filtering fluids for medical applications(including for home and/or for patient use, e.g., intravenousapplications, also including, for example, filtering biological fluidssuch as blood (e.g., to remove leukocytes)), filtering fluids for theelectronics industry (e.g., filtering photoresist fluids in themicroelectronics industry), filtering fluids for the food and beverageindustry, clarification, filtering antibody- and/or protein-containingfluids, filtering nucleic acid-containing fluids, cell detection(including in situ), cell harvesting, and/or filtering cell culturefluids. Alternatively, or additionally, membranes according toembodiments of the invention can be used to filter air and/or gas and/orcan be used for venting applications (e.g., allowing air and/or gas, butnot liquid, to pass therethrough). Membranes according to embodiments ofthe inventions can be used in a variety of devices, including surgicaldevices and products, such as, for example, ophthalmic surgicalproducts.

In accordance with embodiments of the invention, the membrane can have avariety of configurations, including planar, flat sheet, pleated,tubular, spiral, and hollow fiber.

Membranes according to embodiments of the invention are typicallydisposed in a housing comprising at least one inlet and at least oneoutlet and defining at least one fluid flow path between the inlet andthe outlet, wherein at least one inventive membrane or a filterincluding at least one inventive membrane is across the fluid flow path,to provide a filter device or filter module. In an embodiment, a filterdevice is provided comprising a housing comprising an inlet and a firstoutlet, and defining a first fluid flow path between the inlet and thefirst outlet; and at least one inventive membrane or a filter comprisingat least one inventive membrane, the inventive membrane or filtercomprising at least one inventive membrane being disposed in the housingacross the first fluid flow path.

Preferably, for crossflow applications, at least one inventive membraneor filter comprising at least one inventive membrane is disposed in ahousing comprising at least one inlet and at least two outlets anddefining at least a first fluid flow path between the inlet and thefirst outlet, and a second fluid flow path between the inlet and thesecond outlet, wherein the inventive membrane or filter comprising atleast one inventive membrane is across the first fluid flow path, toprovide a filter device or filter module. In an illustrative embodiment,the filter device comprises a crossflow filter module, the housingcomprising an inlet, a first outlet comprising a concentrate outlet, anda second outlet comprising a permeate outlet, and defining a first fluidflow path between the inlet and the first outlet, and a second fluidflow path between the inlet and the second outlet, wherein at least oneinventive membrane or filter comprising at least one inventive membraneis disposed across the first fluid flow path.

The filter device or module may be sterilizable. Any housing of suitableshape and providing an inlet and one or more outlets may be employed.

The housing can be fabricated from any suitable rigid imperviousmaterial, including any impervious thermoplastic material, which iscompatible with the fluid being processed. For example, the housing canbe fabricated from a metal, such as stainless steel, or from a polymer,e.g., transparent or translucent polymer, such as an acrylic,polypropylene, polystyrene, or a polycarbonate resin.

The following examples further illustrate the invention but, of course,should not be construed as in any way limiting its scope.

Example 1

This example describes some of the materials used in the preparation ofthe monomers and polymers.

Maleimide, furan, diisopropylazodicarboxylate (DIAD), triphenylphosphine(Ph₃P), 1-haxadecanol, tetrahydrofuran (THF), ethyl acetate,N-phenylmaleimide, acetonitrile, methanol, Grubbs second generationcatalyst, 3-bromopyridine, and pentane were obtained from Sigma-AldrichCo. and used without further treatment. Dichloropentane, also obtainedfrom Sigma-Aldrich Co., was treated with basic alumina before use.

Example 2

This example illustrates the preparation ofexo-7-oxanorbornene-5,6-dicarboxyimide (C1), an intermediate in thepreparation of the first and second monomers in accordance with anembodiment of the invention.

In a clean 500 mL round bottom flask (RBF) equipped with magneticstirring bar, furan (21.0 g, 309 mmol) was added to a solution ofmaleimide (25 g, 258 mmol) in 250 mL of ethyl acetate. The mixture washeated at 90° C. for 30 h. C1 was obtained as white precipitate fromsolution upon washing with ether (100 mL, 3×) and filtration. The whitesolid was dried under vacuum at room temperature for 24 h. C1 wasobtained as a pure exo-isomer in yield of 29 g, 68%. ¹H-NMR (300 MHz,CDCl₃): δ (ppm) 8.09 (s, 1H), 6.53 (s, 2H), 5.32 (s, 2H), 2.89 (s, 2H).

Example 3

This example illustrates the preparation ofdichloro[1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene](benzylidene)bis(3-bromopyridine)ruthenium(II)(G3) catalyst.

The second generation Grubbs catalyst (G2) illustrated above (1.0 g,1.18 mmol) was mixed with 3-bromopyridine (1.14 mL, 11.8 mmol) in 50 mLflask. Upon stirring at room temperature for 5 min, the red mixtureturned into bright green. Pentane (40 mL) was added with stirring for 15minutes and green solid was obtained. The mixture was cooled in thefreezer for 24 h and filtered under vacuum. The resulting G3 catalyst, agreen solid, was washed with cold pentane and dried under vacuum at roomtemperature to give a yield of 0.9 g, 88% yield.

Example 4

This example illustrates the preparation of a first monomerexo-7-oxanorbornene-N-hexadecyl-5,6-dicarboxyimide.

In a clean 500 mL RBF equipped with magnetic stirring bar, a mixture ofexo-7-oxanorbornene-5,6-dicarboxyimide (C1) (10 g, 61 mmol), Ph₃P (23.84g, 91 mmol), and 1-hexadecanol (17.6 g, 72.7 mmol) were dissolved inanhydrous THF (130 mL) under a stream of dry nitrogen gas. The solutionwas cooled in ice bath. DIAD (22.1 g, 109.3 mmol) was added from adropping funnel drop-wise to the cooled solution. The reaction mixturewas allowed to warm up to room temperature and stirred for 24 h. THF wasremoved by rotary evaporator till dryness to obtain white solid. Thefirst monomer was obtained from the crude as white solid uponcrystallization from methanol (2×) and drying at room temperature undervacuum for 24 h (yield of 18.6 g, 80%). ¹H-NMR (300 MHz, CDCl₃): δ (ppm)6.5 (s, 2H), 5.26 (s, 2H), 5.32 (s, 2H), 3.45 (t, 2H), 2.82 (s, 2H),1.56-1.38 (m, 2H), 1.28-1.1 (m, 26H), 0.88 (t, 3H).

Example 5

This example illustrates the preparation of a second monomerexo-7-oxanorbornene-N-phenyl-5,6-dicarboxyimide.

In a clean 500 mL round bottom flask (RBF) equipped with magneticstirring bar, Furan (29.51 g, 433.5 mmol) was added to a solution ofN-phenyl maleimide (25 g, 144.5 mmol) in 135 mL of acetonitrile. Thesolution was refluxed at 90° C. for 5 h. White crystalline solid wasobtained upon cooling the reaction mixture. The second monomer wasobtained by filtering the solid and purified by recrystallization fromacetonitrile (2×). Yield of 19 g, 76%. ¹H-NMR (300 MHz, CDCl₃): δ (ppm)7.55-7.35 (m, 3H, phenyl), 7.35-7.2 (m, 2H, phenyl), 6.57 (s, 2H), 5.37(s, 2H), 3.05 (s, 2H).

Example 6

This example illustrates the preparation of a diblock copolymer suitablefor preparing a membrane in accordance with an embodiment of theinvention.

The Grubbs 3^(rd) generation (G3) catalyst from Example 3 (34.4 mg,0.039 mmol) was weighed in 40 mL vial with equipped with fluoropolymerresin-silicone septa open-top cap. The catalyst was dissolved inargon-degassed dichloromethane (DCM) (60 mL) and transferred via cannulato a clean 1 L RBF equipped with stirring bar. A solution of the firstmonomer (1.5 g, 3.85 mmol) in DCM (86 mL) was degassed with argon andtransferred into the catalyst solution and shined for 30 minutes. Analiquot of 1-2 mL of the homopolymer formed from the first monomer wastaken after 30 minutes for molecular weight characterization. A solutionof the second monomer (7.9 g, 32.8 mmol) in DCM (208 mL) was degassedwith argon and transferred into the growing homopolymer solution in theRBF, and the contents of the flask were stirred for another 60 minutes.Ethyl vinyl ether (2 mL) was then added to the yellow solution of thediblock copolymer to terminate the polymerization. The resulting polymerwas precipitated in methanol (2 L, 2×) to recover the pure polymer as awhite solid. The polymer was filtered and dried under vacuum at roomtemperature; yield (9.2 g, 98%). ¹H-NMR (300 MHz, CDCl₃): δ (ppm)7.7-7.25 (m, 3H, phenyl), 7.25-6.8 (m, 2H, phenyl), 6.3-5.9 (broad, 1H),5.9-5.3 (broad m, 1H), 5.3-4.9 (broad m, 1H), 4.9-4.2 (broad m, 1H),3.6-3.0 (broad s, 2H), 1.6-1.4 (broad, 2H), 1.4-1.0 (s, 26H), 0.88 (t s,3H).

Example 7

This example illustrates a method of hydrogenating the diblock copolymerprecursor obtained in Example 6 to obtain a diblock copolymer inaccordance with an embodiment of the invention.

The diblock copolymer precursor was dissolved in DCM (15 g in 400 mL).The Grubbs' 2^(nd) generation catalyst (480 mg, 565 mmol) with silicagel substrate (10 g, 40-63 microns flash chromatography particle) andthe precursor solution were transferred to a Parr high pressure reactorand the reactor was charged with hydrogen gas (1500 psi). The reactorwas heated to 50° C. for 24 h. The resulting polymer mixture wasfiltered and precipitated into methanol (2×) to obtain white precipitate(yield 12 g, 80%). ¹H-NMR (300 MHz, CDCl₃): δ (ppm) 7.6-7.45 (m, 3H,phenyl), 7.4-6.8 (m, 2H, phenyl), 4.5-3.55 (broad m, 2H), 3.5-2.6 (broadm, 2H), 2.5-1.6 (broad s, 2H), 1.6-1.4 (broad s, 2H), 1.4-1.0 (s, 26H),0.88 (t s, 3H).

Example 8

This example illustrates a method to characterize the diblock copolymerinvolving the Multi-angle Laser Light Scattering and gel permeationchromatography (GPC).

The homopolymer and the diblock copolymer obtained in Example 6 werecharacterized for their molecular weight and molecular weightdistribution properties by the MALS-GPC technique under the followingconditions:

Mobile phase: Dichloromethane (DCM).

Mobile phase temperature: 30° C.

UV wavelength: 245 nm.

Columns used: three PSS SVD Lux analytical columns(Styrene-divinylbenzene copolymer network), columns have stationaryphase beads of 5 micrometers and has the pore sizes of 1000 A, 100,000A, and 1,000,000 A, and guard columns.

Flow rate: 1 mL/min.

GPC system: waters HPLC alliance e2695 system with UV and RI detectors

MALS system: The DAWN HELEOS 8 system with 8 detectors operating a laserat 664.5 nm.

The chromatograms are depicted in FIG. 1. The diblock copolymerprecursor 2 eluted earlier than homopolymer 1 since it had a highermolecular weight. The diblock copolymer 3 of the invention also elutedearlier than homopolymer 1 since it had a higher molecular weight. Thehydrogenated copolymer 3 has a molecular weight close to that of thecopolymer precursor 2 since the effect of hydrogenation on the molecularweight is rather small as expected.

Example 9

This example illustrates a method for preparing a porous membrane inaccordance with an embodiment of the invention.

A polymer solution containing the diblock copolymer from Example 6 wasprepared by mixing the diblock copolymer with DMF and THF until a clearsolution was obtained. The solution contained the diblock copolymer at 5mass %. The mass ratio of DMF to THF was 60:40.

The polymer solution was spray coated through a nozzle onto a glassplate as a thin film.

Spray coating conditions are as follows: Air spray coating was used togenerate the membrane of a substrate with following general conditions.The substrate was glass. The air pressure was 15 psi. The distance fromthe nozzle to substrate was 20 cm. One layer of thin film was deposited.

The thin films were studied as cast or after annealing. The thin filmwas annealed in a solvent chamber containing DCM vapor for a period of16 hr at low humidity. The film was washed and dried, and then imagedwith atomic force microscopy (AFM) to reveal the nanostructure.

FIG. 2A depicts the AFM height image of the film after spray coating.

FIG. 2B depicts the AFM phase image of the thin film after spraycoating. FIG. 2C depicts the line profile extracted from FIG. 2B.

FIG. 3A depicts the AFM height image of the thin film spray coated andannealed.

FIG. 3B depicts the AFM phase image of the thin film spray coated andannealed.

FIG. 4A depicts the FE-SEM image of the cross-section of the spraycoated film on glass.

FIG. 4B depicts a higher magnification FE-SEM image depicted in FIG. 4A.

From the AFM and FE-SEM images, it can be seen that the diblockcopolymer self-assembled into an ordered structure comprising acylindrical morphology.

The domain size of the block copolymer in the as cast film was about 20to about 30 nm. The domain size of the block copolymer in the annealedfilm was about 60 to about 70 nm.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and “at least one” andsimilar referents in the context of describing the invention (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The use of the term “at least one”followed by a list of one or more items (for example, “at least one of Aand B”) is to be construed to mean one item selected from the listeditems (A or B) or any combination of two or more of the listed items (Aand B), unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A method of preparing a porous membrane comprising a block copolymerof the formula (I) or (II):

wherein: R¹ is a C₁-C₂₂ alkyl group optionally substituted with asubstituent selected from halo, alkoxy, alkylcarbonyl, alkoxycarbonyl,amido, and nitro, or a C₃-C₁₁ cycloalkyl group, optionally substitutedwith a substituent selected from alkyl, halo, alkoxy, alkylcarbonyl,alkoxycarbonyl, amido, and nitro; R² is a C₆-C₂₀ aryl group or aheteroaryl group, optionally substituted with a substituent selectedfrom hydroxy, amino, halo, alkoxy, alkylcarbonyl, alkoxycarbonyl, amido,and nitro; one of R³ and R⁴ is a C₆-C₁₄ aryl group, optionallysubstituted with a substituent selected from hydroxy, halo, amino, andnitro, and the other of R³ and R⁴ is a C₁-C₂₂ alkoxy group, optionallysubstituted with a substituent selected from carboxy, amino, mercapto,alkynyl, alkenyl, halo, azido, and heterocyclyl; and n and m areindependently about 10 to about 2000; the method comprising: (i)dissolving the block copolymer in a solvent system to obtain a polymersolution; (ii) spray coating the polymer solution onto a substrate;(iii) annealing the coating obtained in (ii) in a vapor comprising asolvent or a mixture of solvents to obtain a self-assembled structure;and optionally (iv) annealing or soaking the self-assembled structureobtained in (iii) in a solvent or mixture of solvents to obtain a porousmembrane.
 2. The method of claim 1, wherein R¹ is a C₁₀-C₁₈ alkyl group,optionally substituted with a substituent selected from halo, alkoxy,alkylcarbonyl, alkoxycarbonyl, amido, and nitro.
 3. The method of claim1, wherein R² is a phenyl group, optionally substituted with asubstituent selected from hydroxy, amino, halo, alkoxy, alkylcarbonyl,alkoxycarbonyl, amido, and nitro.
 4. The method of claim 1, wherein R³is phenyl.
 5. The method of claim 1, wherein R⁴ is a C₁-C₆ alkoxy group.6. The method of claim 1, wherein n is about 10 to about 200 and m isabout 50 to about
 2000. 7. The method of claim 6, wherein n is about 83to about 190 and m is about 675 to about
 1525. 8. The method of claim 7,wherein n is about 105 and m is about
 870. 9. The method of claim 1,wherein the diblock copolymer of formula (I) has the followingstructure:


10. The method of claim 1, wherein the solvent system includes a solventor a mixture of solvents selected from halogenated hydrocarbons, ethers,amides, and sulfoxides.
 11. The method of claim 1, wherein the solventsystem includes a solvent or a mixture of solvents selected fromdichloromethane, 1-chloropentane, chloroform, 1,1-dichloroethane,N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone,dimethylsulfoxide, tetrahydrofuran, 1,3-dioxane, and 1,4-dioxane. 12.The method of claim 1, wherein the polymer solution contains about 3 toabout 8% by weight of the diblock copolymer.
 13. The method of claim 1,wherein the substrate is selected from glass, silicon wafer, metalplate, plastic film, woven or nonwoven fabric, and a plastic film coatedon a glass substrate or on or a silicon wafer.
 14. The method of claim1, wherein the substrate is porous.
 15. The method of claim 1, whereinthe annealing is carried out in the presence of a solvent vaporcomprising dichloromethane.
 16. The method of claim 1, wherein theannealing is carried out twice.
 17. A porous membrane prepared by themethod of claim
 1. 18. The porous membrane of claim 17, which is asingle layer membrane.
 19. The porous membrane of claim 18, which is acomposite membrane comprising a first layer and a second layer, thefirst layer comprising the diblock copolymer and ordered pores in acylindrical morphology and the second layer comprising a microporoussupport layer.